This is a revised proposal to study biobehavioral aspects of mood disorders in girls. Specifically, it addresses the increase in rates of unipolar depression in girls that occurs during adolescence. We will contrast the effects of (1) age, (2) the development of secondary sex characteristics (Tannerstage) and (3) the effects of changing levels of six hormones -(a) from the pituitary, follicle stimulating hormone and luteinizing hormone, (b) estradiol (produced largely from the ovaries), and (c) testosterone, and rostenedione, and dehydroepiandrosterone-sulphate, which are produced largely from the adrenals in girls. Based on previous data from our group and a hierarchical model of puberty presented in the proposal, we predict that any apparent effects of age and/or Tannerstage will be better explained by underlying changes in testosterone and estradiol. Such a pattern of results would militate against theories attributing increases in rates of depression in adolescent girls to social effects generated by externally observable changes in secondary sex characteristics. The study is a unique opportunity to examine these issues because the psychiatric diagnostic data have already have been collected on a relatively large (N=438), representative, community sample of female children and adolescents, and the blood samples are already in hand. Funding is sought for two years of support for assay completion and data analysis.